This amp suffered from a loud hum because the 120V mains wires were routed to the power switch on the treble control. I installed a 3-prong cord and moved the mains switch to the back panel, which eliminated most of the hum. I also replaced the electrolytic caps and installed an elevated virtual center tap for the heater winding.
The reverb still hummed a bit but I was able to eliminate it by moving a couple ground wires and altering some of the lead dressing.
To take advantage of the now empty switch on the treble control, I wired in a tone-stack defeat switch that gives the amp a slight gain boost when opened.
